#region Apache License
//
// Licensed to the Apache Software Foundation (ASF) under one or more 
// contributor license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright ownership. 
// The ASF licenses this file to you under the Apache License, Version 2.0
// (the "License"); you may not use this file except in compliance with 
// the License. You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
#endregion

using System;

namespace log4net.Core
{
    /// <summary>
    /// An evaluator that triggers at a threshold level
    /// </summary>
    /// <remarks>
    /// <para>
    /// This evaluator will trigger if the level of the event
    /// passed to <see cref="IsTriggeringEvent(LoggingEvent)"/>
    /// is equal to or greater than the <see cref="Threshold"/>
    /// level.
    /// </para>
    /// </remarks>
    /// <author>Nicko Cadell</author>
    public class LevelEvaluator : ITriggeringEventEvaluator
    {
        /// <summary>
        /// The threshold for triggering
        /// </summary>
        private Level m_threshold;

        /// <summary>
        /// Create a new evaluator using the <see cref="Level.Off"/> threshold.
        /// </summary>
        /// <remarks>
        /// <para>
        /// Create a new evaluator using the <see cref="Level.Off"/> threshold.
        /// </para>
        /// <para>
        /// This evaluator will trigger if the level of the event
        /// passed to <see cref="IsTriggeringEvent(LoggingEvent)"/>
        /// is equal to or greater than the <see cref="Threshold"/>
        /// level.
        /// </para>
        /// </remarks>
        public LevelEvaluator() : this(Level.Off)
        {
        }

        /// <summary>
        /// Create a new evaluator using the specified <see cref="Level"/> threshold.
        /// </summary>
        /// <param name="threshold">the threshold to trigger at</param>
        /// <remarks>
        /// <para>
        /// Create a new evaluator using the specified <see cref="Level"/> threshold.
        /// </para>
        /// <para>
        /// This evaluator will trigger if the level of the event
        /// passed to <see cref="IsTriggeringEvent(LoggingEvent)"/>
        /// is equal to or greater than the <see cref="Threshold"/>
        /// level.
        /// </para>
        /// </remarks>
        public LevelEvaluator(Level threshold)
        {
            if (threshold == null)
            {
                throw new ArgumentNullException("threshold");
            }

            m_threshold = threshold;
        }

        /// <summary>
        /// the threshold to trigger at
        /// </summary>
        /// <value>
        /// The <see cref="Level"/> that will cause this evaluator to trigger
        /// </value>
        /// <remarks>
        /// <para>
        /// This evaluator will trigger if the level of the event
        /// passed to <see cref="IsTriggeringEvent(LoggingEvent)"/>
        /// is equal to or greater than the <see cref="Threshold"/>
        /// level.
        /// </para>
        /// </remarks>
        public Level Threshold
        {
            get { return m_threshold; }
            set { m_threshold = value; }
        }

        /// <summary>
        /// Is this <paramref name="loggingEvent"/> the triggering event?
        /// </summary>
        /// <param name="loggingEvent">The event to check</param>
        /// <returns>This method returns <c>true</c>, if the event level
        /// is equal or higher than the <see cref="Threshold"/>. 
        /// Otherwise it returns <c>false</c></returns>
        /// <remarks>
        /// <para>
        /// This evaluator will trigger if the level of the event
        /// passed to <see cref="IsTriggeringEvent(LoggingEvent)"/>
        /// is equal to or greater than the <see cref="Threshold"/>
        /// level.
        /// </para>
        /// </remarks>
        public bool IsTriggeringEvent(LoggingEvent loggingEvent)
        {
            if (loggingEvent == null)
            {
                throw new ArgumentNullException("loggingEvent");
            }

            return (loggingEvent.Level >= m_threshold);
        }
    }
}
